feat(physics): port retail projectile integration

Add a pure Core projectile driver for retail clock quanta, final-state acceleration, 50-unit velocity clamping, world-space angular integration, full-3D AlignPath, and oriented Setup-local sphere sweeps. Preserve exact success versus set_frame-only failure semantics, independent Contact/OnWalkable state, and full-cell identity across all landblock directions.

Port OBJECTINFO::missile_ignore with explicit weenie/creature metadata, remove the invented transition-step cap, retain PathClipped without arming PerfectClip, and keep authoritative target identity optional. Add malformed-shape/clock, thin-wall, terrain, target-exclusion, frame-spike, failure-state, and boundary conformance coverage.

Retire TS-2 and synchronize the architecture, milestones, roadmap, research oracle, and durable physics memory.

Co-Authored-By: Codex <noreply@openai.com>

docs/architecture/acdream-architecture.md

@@ -146,6 +146,8 @@ src/
       PhysicsDataCache.cs     -> GfxObj / Setup / CellStruct collision data (done, active)
       ShadowObjectRegistry.cs -> broadphase for nearby physics objects (active)
       PhysicsEngine.cs        -> ResolveWithTransition active player path
+      ProjectilePhysicsStepper.cs -> pure retail projectile integration + sweep
+      RetailFrameMath.cs      -> retail full-3D vector-heading frame construction
       CellBsp.cs              -> not a first-class runtime owner yet (L.2e)
     World/
       GameEntity.cs           -> target unified entity, not current reality
@@ -216,7 +218,12 @@ InputDispatcher / PlayerMovementController
 What exists and is active:
 
 - `PhysicsEngine.ResolveWithTransition` is the path used for local player
-  collision resolution.
+  collision resolution and the shared continuous object sweep.
+- `ProjectilePhysicsStepper` is the pure Core driver for retail projectile
+  clock quanta, final-state acceleration, velocity/angular integration,
+  AlignPath, Setup-sphere transition sweeps, and collision response. It owns no
+  live entity, network, rendering, or App state; the App controller supplies
+  those boundaries.
 - `BSPQuery` contains the partial retail-style BSP collision dispatcher used by
   the transition path.
 - `TransitionTypes` carries `SpherePath`, `CollisionInfo`, `ObjectInfo`,